What’s the point of a rational argument? To give someone a good reason to believe something. A sufficiently good argument gives us a good reason to believe something is true. It is better for us to have beliefs that are supported by good arguments in the sense that they are more likely true based on our limited understanding of the world, but it is possible for them to be false.
I will describe good arguments in more detail, explain why they are important, and give criteria for them.
What are good arguments?
Before knowing what good arguments are, it can be helpful to know what arguments and rational arguments are.
Arguments are reasoning processes made explicit. Arguments have premises (the reason to believe something) and conclusions (the belief we want to argue for). An example of an argument is “All lizards are reptiles. All reptiles are animals. Therefore, all lizards are animals.”
Arguments are not always good reasons to believe anything, but rational arguments are meant to give us a good reason to believe something. Sometimes people want to manipulate others into believing something by using arguments. That’s not what rational arguments are about. A rational argument is supposed to to tell us what we should think is true. Rational arguments should help us know what is likely true. Having beliefs based on rational arguments should help us have more true beliefs.
People who try to give rational arguments don’t always succeed. They don’t always give us a good reason to believe something. A person can be sincere and tell us that all mammals give live birth to their young based on the fact that innumerable mammals give live birth to their young. However, the argument fails because we have discovered various mammals that lay eggs (such as the platypus).
A good argument is a successful rational argument. It genuinely gives us a good reason to believe something based on the information that’s available to us. Scientists have good arguments for their best theories (such as Einstein’s theory of relativity) because they have a good reason to believe their best theories are true. We have a good reason to believe something based on a good argument because beliefs that are supported by good arguments are more likely true than beliefs that aren’t. The conclusions of good arguments are rarely guaranteed to be true, but people who reject the conclusions of sufficiently good arguments will be more likely to have a false belief.
Consider someone who thinks the following:
- I should feed my young child healthy food.
- It would be healthy for my young child to eat this apple.
- If I should feed my young child healthy food and it would be healthy for my young child to eat this apple, then I should feed my child this apple.
- Therefore, I should feed my young child this apple.
This could be a good argument. There are probably a lot of children we should give apples to. Even so, we could imagine that the apple might be secretly poisoned. In that case the second premise will be false. The fact that a premise is false does not necessarily mean it’s not a good argument because we might have no reason to believe it’s false. It would be reasonable to assume that an apple is not secretly poisoned, and it certainly wouldn’t be reasonable to expect all of our food to be secretly poisoned.
Even if the second premise is false, this is still likely a good argument given most situations caregivers find themselves in. It would only fail to be a good argument whenever we have a good enough reason to doubt one of the premises to be true.
The same is true of good arguments for our best scientific theories. At one point we thought Newton’s theory of physics was entirely true and complete, and we didn’t yet have a good reason to adopt Einstein’s theory of relativity. Good arguments gave us a reason to believe something false. Now we know better.
Also, it could be useful to note that good arguments are related to attaining knowledge, which is classically defined as justified true belief. If you have a belief that is properly justified and true, then you know it’s true. Good arguments help assure us that our beliefs are properly justified. If we have a good argument for a true belief, then we know it’s true.
Consider the following argument—“Every living mammal we’ve ever seen has a brain. Therefore, all living mammals probably have a brain.” This seems to be a good reason to believe that all living mammals have a brain, and anyone who believes that all living mammals have a brain based on this argument could be said to “know that all living mammals have a brain.”
Finally it could be useful to note that some good arguments are sufficiently good to give us a sufficient reason to believe the conclusion and other good arguments are merely good enough to provide us with a conclusion that would we would be justified to believe.
Consider that we know all living dogs have a brain based on innumerable observations and scientific findings. Agreeing to the conclusion seems like it’s a rational requirement because the argument is sufficiently good. Disagreeing with the conclusion seems irrational.
Other beliefs are optional because there’s a good argument for the belief, but the argument is not sufficiently good to make the conclusion a rational requirement. It seems like the belief that intelligent life exists on another planet could be a rational belief based on our knowledge of how vast the universe is, but we don’t know for sure. If someone is undecided about it, I wouldn’t say she is being irrational.
Sometimes it might even be rational for two people to disagree based on their own understanding of the world because their opposing conclusions are both supported by good arguments. Perhaps there are times when two different scientific hypotheses are supported by the data and we can’t yet be sure which one is true. That might be a time when it would be rational for various scientists to side with a different hypothesis and disagree about which one is probably true.
Why good arguments are important
Having beliefs when they are supported by good arguments helps assure is that our beliefs are more likely true than if we form our beliefs based on poorly reasoned arguments. Many people will say that’s enough to know that good arguments are important. They would say that we should often use good arguments and we need to base our beliefs on those good arguments. They could say that we want to know what we should believe, and we should believe the conclusions of good arguments rather than the conclusions of poorly reasoned arguments.
However, there might be some people who don’t care about what’s true. Why should we want to believe what’s true? Consider the following answers:
- There’s something valuable about having knowledge, and good arguments help assure us that we have knowledge.
- To reject good arguments and prefer to have beliefs based on poor reasoning is irrational. People who are consistently persuaded to believe things too easily are gullible and people who consistently refuse to believe things based on sufficiently good arguments are close-minded.
- There are people who want to manipulate us using poor reasoning. People are fooled into wasting their money on ineffective medicine, wasting their time believing in cults, and opposing good science because they believe things based on poor reasoning rather than good reasoning. To understand what makes something a good argument and to try to have beliefs based on good arguments can help people avoid being manipulated.
- We want to satisfy our desires, but we are often wrong about how to do that. Having good reasons to believe that certain actions will satisfy our desires will help us know how to do it.
Criteria of good arguments
We know that certain arguments are good and others are bad, but it’s not always obvious. Sometimes we even think an argument is obviously good when it’s actually poorly reasoned and vice-versa. Philosophers and logicians have been researching the criteria of good arguments, but they aren’t done yet. We are still learning more about what is required of a good argument.
The major types of criteria we can use to determine if an argument is good is the following:
- The argument must not be fallacious.
- The premises must be justified.
- The conclusion must follow from the premises.
The argument must not be informally fallacious.
Many philosophers who study argumentation talk about “informal fallacies.” These fallacies are various errors in reasoning, which tells us improper ways people sometimes reason about things. There are hundreds of fallacies, such as the straw man fallacy.
The straw man fallacy is an error in reasoning that we comment when we attribute a poorly reasoned argument to someone else that was never actually argued for. The poorly reasoned argument could either be taken to be obviously bad or it can be refuted by another argument. The argument that’s rejected is worse than other arguments for the same conclusion. (Sometimes better arguments were already given by the person that the poorly reasoned argument was falsely attributed to.)
For example, imagine that Jennifer argues that “we shouldn’t torture people because there’s no good reason to cause that much pain, and we shouldn’t cause pain unless we have a good reason to.” Tom then replies, “Jennifer says that we shouldn’t torture terrorists because we should never cause anyone pain, but we know that we have to throw hardened criminals in prison, even though it can cause the criminals pain.” Notice that Jennifer did not actually say that we should never cause pain. What Tom said is irrelevant to Jennifer’s argument, so he failed to give us a reason to reject her argument.
The straw man fallacy is what happens when we egregiously violate the principle of charity, which is the principle that states that we should properly represent other people’s arguments, and that we should be careful to understand their arguments properly. We should also generally try to refute the strongest arguments for a conclusion rather than the worst. If we reject the worst arguments for a conclusion, then the best arguments for that conclusion could still give us a good reason to agree with it.
The premises must be justified.
What exactly it means for a premise to be justified is not entirely clear. They must be properly justified. Ideally, we would have a good reason to think each premise is probably true. In a debate, the premises of an argument need to be either argued for or the person we want to persuade needs to agree with our premises.
Consider the following argument:
- All reptiles are animals.
- All dogs are reptiles.
- We should believe that all dogs are reptiles because dogs breathe oxygen and have a tail, just like reptiles.
- Therefore, all dogs are animals.
The conclusion is true, but the argument is not rationally persuasive because some of the premises are false. We know dogs are not reptiles. The premise that states “all dogs are reptiles” is poorly argued for (the fact that dogs breathe oxygen and have a tail does not mean that dogs are reptiles). That justification is not appropriate, so the second and third premises are ultimately not justified in the sense that would be required of a good argument.
Now consider another argument:
- All dogs are mammals.
- All mammals are animals.
- Therefore, all dogs are animals.
I believe this to be a good argument. It is possible to justify each premise with more arguments, but it is obvious enough that the premises are all true that further justification seems unnecessary in most contexts. I would consider the premises to be justified, even without more arguments being given.
Also keep in mind that we can’t justify all our premises with more arguments or we would have to have infinite arguments. Every argument has premises, and we can have an argument for every premise. That means one argument will have at least one premise and an argument will have to be given for that premise, but the second argument will also have an argument for it (including at least one premise) on and on forever. It is absurd to think a good argument will require infinite arguments for the premises. My solution is that it is possible to have a properly justified premise without an argument for that premise. The premises we consider to be justified are generally those we agree with. We generally don’t require arguments for conclusions we already agree with.
The conclusion must follow from the premises.
If the premises are true, then the conclusion is true or likely true. There must be something about the premises that helps assure us that the conclusion follows from them. There are at least two different ways that a conclusion can follow from the conclusion depending on the type of argument we give. Inductive and deductive arguments have somewhat different requirements.
Inductive arguments are supposed to have probable conclusions based on the evidence available. For example, we know dropped objects will fall in the future because they always fell in the past (given the right conditions). Good inductive arguments must be logically strong, which means that it is unlikely for the premises to be true and the conclusion false at the same time. Considering that all objects fell in the past, it is unlikely that they won’t fall anymore in the future.
A good inductive argument is strong and the premises are justified, so a good inductive argument will give us a reason to agree with the conclusion in proportion to how well supported the premises are and how strong the argument is. If we know the premises are true and the argument is strong, then we know the conclusion is probably true.
Deductive arguments are supposed to have true conclusions when the premises are true. For example, the above argument that all dogs are animals. If it’s true that “all dogs are mammals” and “all mammals are animals,” then it must also be true that “all dogs are animals.” Good deductive arguments must be logically valid, which means they have an argument form that assures us that it’s impossible for the premises to be true and the conclusion false at the same time.
A good deductive argument is valid and the premises are justified, so a deductive argument will give us a reason to agree with the conclusion in proportion to how well supported the premises are. If we know the premises are true and it’s valid, then we also know the conclusion is true. If we agree with the premises, but disagree with the conclusion, then we will have inconsistent beliefs.
Logical validity is the focus of formal logic.
Good arguments are successful rational arguments. A good argument requires that a reasoning process is done the right way. If an argument is sufficiently good, then we say that people should agree with the argument, and we might even say people are being irrational who disagrees with it.
We need to understand and use good arguments because we want to know what we should believe. To have beliefs for the wrong reasons is irrational. To consistently form beliefs based on insufficient evidence is gullible, and to consistently refuse to form beliefs based on sufficiently good arguments is close-minded.
Finally, we can study various criteria of good argumentation. We can study informal fallacies, the difference between properly and improperly justified beliefs, and when premises are properly relevant to the conclusion. We can find out how to know when an informal argument is strong, or when a deductive argument is logically valid.